#!/usr/bin/env python3


def main():
    if int(input()) >= 30:
        print('Yes')
    else:
        print('No')


if __name__ == "__main__":
    main() def main():
    if int(input()) >= 30:
        print('Yes')
    else:
        print('No') main if int(input()) >= 30:
        print('Yes')
    else:
        print('No') int(input()) >= 30 int(input()) int input() input 30 print('Yes') print 'Yes' print('No') print 'No' if __name__ == "__main__":
    main() __name__ == "__main__" __name__ "__main__" main() main def main():
    if int(input()) >= 30:
        print('Yes')
    else:
        print('No') def main():
    if int(input()) >= 30:
        print('Yes')
    else:
        print('No') main
#!/usr/bin/env python3


def main():
    if int(input()) >= 30:
        print('Yes')
    else:
        print('No')


if __name__ == "__main__":
    main()
